Abstracts

Ecological network patterns are influenced by diverse processes that
operate at different temporal rates. Here we analyzed if the coupled effect
of local abundance variation, seasonally phenotypic plastic responses and
species evolutionary adaptations might act in concert to shape network
patterns. We studied the temporal variation in three interaction properties
of bird species (number of interactions per species, interaction strength
and interaction asymmetry) in a temporal sequence of 28 plant-frugivore
interaction networks spanning two years in a Mediterranean shrubland community.
Three main hypotheses dealing with the temporal variation of network properties
were tested, examining the effects of abundance, switching behavior between
alternative food resources and morphological traits in determining consumer
interaction patterns. Our results demonstrate that temporal variation in
consumer interaction patterns is explained by short-term variation in resource
and bird abundances and seasonal dietary switches between alternative resources
(fleshy fruits and insects). Moreover, differences in beak morphology are
associated with differences in switching behavior between resources, suggesting
an important role of foraging adaptations in determining network patterns.
We argue that beak shape adaptations might determine generalist and specialist
feeding behaviors and thus the positions of consumer species within the
network. Finally, we provide a preliminary framework to interpret phylogenetic
signal in plant-animal networks. Indeed, we show that the strength of the
phylogenetic signal in networks depends on the relative importance of abundance,
behavioral and morphological variables. We show that these variables strongly
differ in their phylogenetic signal. Consequently, we suggest that moderate
and significant phylogenetic effects should be commonly observed in networks
of species interactions.